The overall objective is to improve the safety and health of firefighters and rescue workers who use self-contained breathing apparatus (SCBA) in hazardous environment. The specific aim is to develop an electromechanical pressure regulator that assures positive pressure in the SBA facepiece even during strenuous activity. Positive pressure is essential to protect health and safety, because the facepiece pressure keeps out potentially poisonous gases from the environment. The proposed electromechanical pressure regulator overcomes the drawbacks of conventional, mechanical regulators. The three key innovations are: (1) a lightweight, piezoelectrically actuated, electromechanical valve, (2) an innovative electronic control and actuation system that consumes ver little power and (3) a power generating system driven by a trickle flow of compressed air that provides all the power required by the regulator. The rapid responses and wide control range of the electromechanical valve prevent over-breathing. The electronic control unit can warn the user of falling pressure in the mask. Phase I proved feasibility by fabricating a proof-of-concept regulator and testing it under extreme conditions using a SCBA facepiece and a breathing machine. In Phase II we will develop and demonstrate prototype regulators for commercial SCBAs which meet all relevant NIOSH and NFPA standards. PROPOSED COMMERCIAL APPLICATIONS: The primary applications is for a pressure-demand, positive-pressure, self-contained breathing apparatus worn by firefighters and hazardous materials workers. The device can be incorporated into new SCBA units and can also be retrofit to units already in the field. We estimate the potential market to be in the range of 10,000 to 100,000 per year. Create has teamed with one of the largest manufacturers of SCBAs to commercialize the electromechanical SCBA regulator.